Web tensioning means



March 27, 1934. I g, A DlCKHAUT 1,952,913

WEB TENS IONING MEANS Filed April 3 1928 2 Sheets-Sheet 1 18 INEENTOR. 1 5 1 6 w 39) BYKQMMI/ KQLLMAA/ WM 1 9 v I v ATTORNEYS.

March 27, 1934; c p c u-r 1,952,913

WEB TENSIONING MEANS Filed April 5, 1928 2 Sheets-Sheet 2 INJ/ENTOR.

BY I A TTORNEYS.

Patented Mar. 27, 1934 UNITED STATES PATENT OFFICE John Waldron Corpo N. J., a corporation ration, New Brunswick, of New Jersey Application April s, 1928, Serial No. 266,908

1 Claim.

This invention relates to web tensioning devices for use in winding operations.

The object of the invention is to provide methods of and means for applying a uniform web tension to a roll of unwinding material and automatically compensating for variations in the load. It is apparent that if no speed controlling mechanism were employed to govern the unwinding of a roll of web material, the tension on the web for any given speed would be measured solely by the size of the roll. As the roll diminishes in diameter the load would increase and the tension on the web correspondingly increase. Since the load would vary indirectly in proportion to the constantly diminishing roll, the tension on the web would be ever changing.

In an endeavor to overcome this condition and obtz in a uniform feed from an unwinding roll, various means have heretofore been provided for varying the tension of the web by braking the roll. However, unless the effect of such braking is to maintain a uniform tension, the web will at times unwind too fast and become loose, or will receive too much tension and be injured. The

gist of applicants invention is to provide a governing arrangement whereby a uniformly increasing load increment is removed fr'omthe uniformly diminishing load represented by the unwinding roll, so that the load, speed, and tension on the web remain constant throughout an unwinding operation.

A feature of the invention resides in the provision of a floating roller adaptedto tension the web and a counterweight for determining the tension applied by said roller. The floating roller and counterweight are designed to be variably adjusted to 'provide a compensating tension to the web beyond the limits of the usual load if a greater or smaller roll of material is used.

A further feature provides for continuous operation by controlling-the braking efl'ect upon a plurality of rollers from a single floating roller, thus as one roller runs out, the web of a fresh one may be applied to the web running out and the operation continued without shutdown of the machine.

Another feature provides for tensioning a web ,by the use of a floating. roller in combination with a hand-adjusted braking means controlled by a second floating roller, the tension on the web determining the position of both rollers.

Other features for c rfyins out the objects of the invention in a number of forms will be apparent from the following description read in conjunction with the accompanying drawings in which:

Figure 1 is a diagrammatical illustration of an arrangement incorporating my invention in which means controlled by a single floating roller apply equal tension to the webs of a plurality of rolls of material;

Fig. 2 illustrates tensioning means roll of material;

Fig. 3 is a view similar to Fig. 1 showing the application of a web tension to a single roll;

Fig. 4 illustrates an alternate form of braking means in a similar arrangement; and

Fig. 5 represents a modified arrangement in which hand adjusted tensioning means are employed in part.

Considering the drawings, similar designations referring to similar parts, numeral 6 represents a bundle of sheet material mounted on shaft 7 on which is fixed gear 8. Friction wheel 9 is secured to gear 10 which meshes with gear 8. Brake segments 11 and 12 are hinged at 13 and fit about the friction wheel. At extremity 14 of segment 12 is provided a fastening turn buckle graphically the effect of my on the web of an unwinding 65 15 adapted to engage within arm 16 pivotally secured to extremity 17 of friction element 11.

As is evident, the arm 16 and turn buckle 15 are swingable on the pivots in the extremities of the friction'elements. It is patent that a downward movement of arm 16 will exert a pressure on the turn buckle causing the elements to apply a pressure or braking effect upon the friction wheel. Bundle of material 6 mounted on shaft 7* is provided with a gear 8 meshing with gear 10 secured to friction wheel 9 which is similarly controlled by an identical friction braking means as is friction wheel 9. Arms 16 and 16 are connected by links to bar 17* pivotally secured to lever 18 5 which is attached to and swings about fixed pivot 19. .Lever 18 is hingedly attached to actuating element 20 secured at pivotal connection 21 .to floating roller 22. This double roll arrangement, as'illustrated, allows the process to be carried on almost continuously, since a new web may be made fast to the end ofthe old web without shutting down the operation. The web running out is noted by the dotted line, the new web'23 having been spliced. It is understood, of course, that in a process requiring two or more webs independently controlled, each .web would need its own floating roll and friction arrangement.

Upon leaving bundle 6, web 23 passes over fixed guiding roller 24 under floating roller 22 over a second fixed guiding roller 25 and then passes on to be utilized as desired. Floating roller 22 is mounted on free shaft 26 on which is also mounted guide gear 27. To control the movement of the floating roller guide opening 28 is provided within which roller 22 moves. Gear 27 is adapted to mesh with the teeth of rack 29 and thus assures accurate alignment of. the roller in its movement with respect to the fixed rollers.

- The weight of the floating-roller 22 together with the braking effect on the bundle determines the tension in the web 23. In "drder to provide for variations in adjustment, the roller 22 has a counterweight 30 which may be'gvaried in accordance with the amount of tension desired in the web.

In practice the weight 30 is adjusted until the position of the roller 22 is such that the braking effect applied at the shaft 7 is sufficient to produce the proper tension when a constant pull is exerted on the web leaving the roller 25. As the bundle 6 decreases in diameter, the force acting through the web to rotate the bundle would increase proportionately assuming a constant braking effect on the shaft 7. This would increase the tension in the web and cause the roller 22 to rise together with the bar 20 and the bar 18' to release the pressure on the brake drum 9 and consequently the braking effect on the shaft 7. The diminished pressure on the brake drum is just sumcient to compensate for the decrease in the diameter of the bundle so that the tension in the web is maintained constant at all times. Obviously, if for some reason the tension in the web were reduced, the roller 22 would drop, lowering .the bar 18, thereby increasing the braking efiect on the shaft 7 and consequently the force necessary to turn the bundle 6. This would return the tension to its proper value. I

The counterweight 30 provides a ready means for adjusting the tension in the web 23. Obviously, fora given weight the tension in the web is constant if the roller 22 is stationary when acted upon by its own weight and the tension in the web, since under these circumstances the braking effects on the shaft 7 is constant. Now, if the counterweight 30 is reduced, the effective weight of the roller 22 is increased. The tension in the web must therefore be increased to restore equilibrium. This occurs when the roller 22 drops under the influence of its increased effective weight and applies additional braking effect to the shaft 7 through the links 20, 18, 17 and the brake bands 11 and 12.

The variations in tension in the web 23 result from the variations in the radius of bundle 6 and effect upon the shaft 7 is diminished at a constant rate. The force applied through the web 23 necessary to turn the .bundle with the diminishing braking effect will also diminish at a constant 'rate. The tension in the web 23 due to this force may be represented by the line 33 in Fig. 2. With proper adjustment of the machine, the amount by whichthese forces change may be made equal so that the resultant tension in the web 23 is substantially constant as indicated by line 34 in Fig. 2. The counterweight 30 may be increased or diminished in weight by changing the number of weight segments of which it is composed and roller 22 may also be made heavier or lighter by varying the weight on shaft 26. For bundles of different. size, it may be necessary to adjust the weights of the floating roller and the counterweights to insure sufficient tension within the limits desired.

In Fig. 4 a system similar to that of Fig. l is illustrated except that a different form of braking means is employed. For some materials, it is found desirable to use a simple friction band 35 having one end fixed and the other end secured to bar 17. The action is the same as when friction elements embracing the wheels are used. A downward movement of bar 17 will apply greater friction and a release of the tension on bar 17 will reduce the braking effect. Inasmuch as in an unwinding operation the pull on bar 17 would uniformly decrease as the roll is unwound, the bands 35 are adjusted so that they are under tension when the roller 6 has its minimum diameter. Under all other conditions, namely, when the roller has a larger diameter, the band 35 will be under tension and will adequately serve to effectively apply the required pressure on the wheels.

Under some circumstances, the web 23 is not of uniform thickness, one edge being thicker than theother. Obviously, if tension is applied to a web of this character, it will be transmitted only by the thick edge of the web and not over its entire width. Fig. 5 illustrates the combination of a hand adjusted friction roller and floating 110 roller arrangement whereby the force tensioning the web may be made to function substantially over its entire width. As in Fig. 1 web 23 passes from the bundle 6 over fixed rollers 24 and 25 carrying a movable roller 22 in the resultant loop.

Aotuating element 20 is thus controlled in its movement by the floating roller 22 and applies a braking effect through the friction wheel 9 which may be mounted directly on the shaft of the bundle. The roller 22 may be equipped with guides and counterweights as in Fig. 1, although these have not been shown. Afterleaving the fixed roller 25, the web passes between a plurality of'rollers 36 and 37, by means of which additional tension is applied to the web. The roller 37 is equipped with a handwheel 38 by means of which it is adjustably positioned with respect to the roller 36 in such a manner that pressure may be applied to the web 23 uniformly over its entire width. From these rollers, the web passes over the fixed rollers 39 and 40 and ,under the floating roller 41 which controls the braking effect on the roller 36 in all respects similar to the manner in which the floating roller operates to apply braking effect in Fig. 1. Assuming that it is desired to have the web under a constant tension as it leaves the roller 40, any fraction of this tension may be applied by the rollers 36 and 37 where it will be uniform over the entire width of the web while the remainder. may be applied as the web leaves the bundle 6. This latter amount may be sufficiently small so that if it is applied at one edge of the web, little danger of breaking will result.

It is apparent that the tension in the web 1eav ing the fixed roller .40 is the sum of the tensions applied at the rollers 36and 37 and that applied at bundle 6. The floating roller 41 is adjusted to apply a braking pressure upon the roller 36 which is sufficient to maintain the desired tension in the web as it leaves the roller 40. As mentioned above, part of the total tension is applied through the rollers 36 and 37. The tension applied at this point will vary with variations in the braking effect on the roller 36. As the web 23 leaves the bundle 6 its tension may be adjusted by the floating roller 22 and the braking effect upon the shaft of the bundle 6 in the manner described in connection with the structure of Fig. 1. The roller 22 may be provided with a counterweight to give a suitable range of adjustment, and if desired the brake drum 9 may be applied directly to the shaft of the bundle 6 instead of through a gear train as in Fig. 1. Either expedient may be used. The floating roller 22 functions to maintain the tension in the web to the left of the roller 36 at the desired fraction of the full tension. However, should this tension vary, the variation will be immediately transmitted to the web to the right of the roller 36, under which circumstances the floating roller 41 will operate to vary the braking efiect on the roller 36 and consequently the tension applied at this point. As the tension in the web leaving the bundle shaft varies therefor the floating roller 41 actuates the roller 36 to supply the differential necessary for maintaining a constant tension on the web leaving the roller 40.

As mentioned above this arrangement is particularly valuable if the web is not of uniform thickness, the tension being applied across the entire width of the web, rather than at the bundle shaft alone. In processes where the point of tension is a considerable distance away from the processing machine, this auxiliary arrangement is deemed well fitted to compensate for variation in tension which would occur, as heretofore explained, if only the arrangement controlled by roller 22 were employed.

It will be apparent that various arrangements may be employed in which a counterweight or similar means are provided to compensate for variations in web tension. It should be understood that applicant does not limit himself to the forms herein illustrated and reserves the right to any system wherein compensating means including a counterweight or equivalent devices are employed to control the load, speed and web tension in a winding operation.

Having described my invention what I claim as new and desire to secure by Letters Patent is:

A device for controlling web tension, comprising a plurality of shafts adapted to be mounted on winding rolls, a gear mounted on each of said shafts, braking means geared to each of said gears, a floating roll supported from the web, a lever attached to said floating roll, means associating said lever with each of said braking means, a counterweight roll above said floating roll, a counterweight, a belt connecting with said floating roll and said counterweight, and means for separately associating the web from each of said unwinding rolls with said floating roll to support the latter, said floating roll functioning to control the web tension of the winding rollwith which it is associated by coaction with the braking means associated with that roll.

CHARLES A. DICKHAUT. 

